Method and kit for treatment of components utilized in a crude oil service operation

ABSTRACT

A method and kit for treatment of a stainless steel or other nickel alloy component utilized in a crude oil service operation including cleaning a surface of the component to remove surface contamination; drying the cleaned surface of the component; applying a coat of Self-Assembled Monolayer of Phosphonate (SAMP) to the cleaned and dried surface of the component to form a treated component; and installing the treated component into a section of a crude oil service operation. The coating reduces paraffin/asphaltene deposition on the component. The kit includes a cleaner wipe impregnated with a cleaning substance for cleaning the component; a nano-coating wipe impregnated with a SAMP for applying a nano-coating of the SAMP to the component; and instructions for treating said component utilizing the cleaner wipe and the nano-coating wipe.

CROSS-REFERENCE TO RELATED APPLICATION DATA

This utility application claims priority to U.S. Provisional PatentApplication Ser. No. 61/770,963 filed Feb. 28, 2013, which isincorporated herein by reference for all purposes.

FIELD OF THE INVENTION

The present invention relates to paraffin and asphaltene deposition oncomponents used in crude oil service operations. More particularly, thepresent invention relates to a method and kit for surface treatment ofcooperating, controller or sensor components used in crude oil serviceoperations to reduce paraffin/asphaltene deposition.

BACKGROUND OF THE INVENTION

Paraffins, more commonly referred to as alkanes, are the chemical familyof saturated hydrocarbons that result from combining CH₂ groups insuccession. Additional CH₂ groups are added to form straight-chainparaffins.

The term “wax” simply refers to saturated hydrocarbons that contain morethan 16 carbon atoms in the paraffin series (C₁₆-C₄₀) and are in a solidstate at room temperature. The majority of waxes present in crude oilare considered synthetic paraffin waxes with non-oxidized saturatedalkanes.

Paraffins may exist in crude oil in all three states. At standard roomtemperature, C₁₆+n-paraffins generally exists in a solid form andsolidify to form deposits. Wax is the product of paraffin deposition, soin the industrial context, “wax” and “paraffin” are often usedinterchangeably.

Therefore, “paraffin wax deposition” refers to the solid form ofparaffins that solidify to cause deposition.

Because asphaltene is typically talked about in the same context asparaffin, it is important to understand what asphaltene is and why it isproblematic to the crude oil service operations. Asphaltene is thematerial present in petroleum that is insoluble in n-paraffins butsoluble in aromatic solvents. Asphaltenes cause catalyst deactivationand sediment formation.

Tars or asphaltenes occur in many crudes as colloidally suspended solidparticles. Precipitation takes place when the crude loses its ability tokeep those particles dispersed. Many of the same factors affectingparaffin deposition (discussed below) also affect asphaltene deposition.

Paraffins precipitate out of waxy crudes when there is a slight changein equilibrium conditions, causing a loss of solubility of the wax inthe crude. A lowering in temperature is the most common cause ofparaffin precipitation.

Thus, hydrocarbon liquids, including both crude oils and condensates,form a paraffin or asphaltene solid phase when process temperatures fallbelow the cloud point (or Wax Appearance Temperature) of the liquid.While this normally occurs in colder temperature services, it may alsooccur in any process where the combination of complex compositionfactors, such as API gravity, pressure/temperature variables and otherfactors favor deposition.

The presence of asphaltenes increases the difficulties for paraffin waxtreatments because these structures are almost always found inassociation with waxes when they are retrieved from wells, storagetanks, or pipelines (Becker J. R. 1997, Crude oil waxes, emulsions, andasphaltenes. Tulsa, Okla.; PennWell Publishing Company). While paraffinwax deposition may be reduced by increasing the flow velocity of crude,increasing fluid velocities increases the likelihood of asphaltenedeposition.

Further, studies show that the amount of asphaltene precipitationdecreases as the number of carbons forming straight-chain paraffinsincreases. In other words, treatment of paraffin wax could escalate theprecipitation of heavier, problematic asphaltene compounds. Therefore,treatment of paraffin and asphaltene deposition must both be consideredin the balance.

Once formed, these paraffin/asphaltene solids will typically deposit ontank-mounted level sensors and instrumentation. This deposition presentsa potential safety hazard when critical operational and/or safetysensors are affected. This may cause a loss of billions of dollars peryear worldwide through the enormous cost of remediation, reduced ordeferred production, well shut-ins, equipment replacements and/orabandonments, equipment failures, extra horsepower requirements, andincreased manpower needs.

The modern petroleum industry has developed new technologies forcontrolling the deposition of petroleum paraffin and asphaltenes,particularly in wells, storage tanks, and pipelines. However, thesetechnologies have been less effective on sensitive tank level sensors,flow sensors, and other instrumentation. Traditional methods ofmanagement and remediation have been established for many years andinclude the following:

a. Chemical Treatments and Additives: While chemical treatments help tomanage solids deposition in connected lines, instrument tubing andstorage tank internal components, some chemicals do not suspend theparaffin indefinitely and may be damaging to the environment.

b. Hot Oiling: Hot oiling is one method often employed for removingdeposition in storage tanks Paraffin and asphaltene buildup is handledby periodically pumping very hot oil, augmented by cleansing additives,into the vessels in order to melt the accumulations from tank walls,sensors and internal equipment.

c. Manual Cleaning: During normal maintenance operations, internallymounted equipment may be periodically subject to manual cleaning Thistypically involves removal of sensors, instruments, etc. fromout-of-service tanks and process equipment for cleaning Alternately,personnel may physically enter out-of-service tanks to perform thecleaning with sensors and equipment in place. These methods typicallyinvolve considerable expense in time and labor for taking equipment outof service, the cleaning process itself, and management of safetyassociated with hazardous conditions, including hydrogen sulfide (H2S)exposure.

However, these procedures are labor and cost intensive and are not veryeffective with sensitive sensors and instrumentations. The solution isto avoid wax and asphaltene depositions in the first place.

The AP (Anti-Paraffin) Coating composition of the present inventionprovides a unique and cost-effective way for petroleum facilityowner/operators to address common paraffin/asphaltene deposition oncooperating stainless steel and nickel alloy sensor components andinstrumentation. It is anticipated that the present method may beutilized with a wide range of metals as well as non-metallic components.

The present invention is a new application of a modified, existing,chemical technology representing a significant potential for reductionin typical labor and costs of paraffin/asphaltene remediation incritical process instrumentation and the elimination of associatedhazards. Using available nano-coating materials applied to cooperatingsurfaces of subject components produces permanent changes in themolecular characteristics of subject component metal, wetted partsand/or entire sensor assemblies, making them highly resistant to solidsdeposition in the extreme process environments normally encountered inpetroleum production facilities. Again, the key strategy is to avoid theinitial affixation of the paraffin and asphaltene deposits on thesurface subject components.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a diagram of the present invention method showing theprocess steps.

FIG. 2 is the perspective view of a foil packet of the present inventivekit.

FIG. 3 is a basic illustration of some components of a digital levelsensor described in this application.

FIGS. 4A-4F are illustrations of capacitance sensors which have beentreated along exposed surfaces with the anti-paraffin coatingcomposition of the present invention.

FIGS. 4A-4C illustrate capacitance sensors having cylindrical outerhousings.

FIGS. 4D-4E show an alternative embodiment of a capacitance sensorhaving a generally rectangular outer housing.

FIG. 4F is a perspective view of the embodiment of FIGS. 4D and 4E.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The present invention to reduce paraffin/asphaltene deposition onstainless steel and nickel alloy components utilizes a composition knownas a Self-Assembled Monolayer of Phosphonate (SAMP). SAMP iscommercially available from a wide range of suppliers. One such supplieris Aculon, Inc., San Diego, Calif. Typically, SAMP is utilized with analcohol-based carrier which allows for rapid drying. It is anticipatedthat the SAMP may be combined with a glycol carrier for use in thetreatment of components used in crude oil service operation.

A monolayer is a nanoscale coating that is one molecule thick or 1-4nanometers in thickness (1 nm=1×10−9 meters). A phosphonate is aphosphorous acid connected with a carbon-based group through a highlystable phosphorus carbon bond.

The phosphonic acid reacts with the component surface through stablemetal phosphorus bonds, and the carbons are chosen for their non-stickchemical functionality. The SAMP is covalently bound to the substrate,forming a durable, low-surface tension, non-stick surface. Thispermanent chemical bond is highly stable under ambient conditions.Currently, an alcohol-based carrier is combined with the SAMP in someapplications, but using a glycol-based carrier is unique in crude oilenvironments.

Through standard Dyne pen testing, surface energy is shown to besignificantly and permanently reduced through application of anano-coating to the tested component. Field trials with componentstreated via the present inventive process indicate a significantreduction of paraffin/asphaltene deposition on stainless steel sensorcomponents installed in crude oil storage tanks operated in lowacidity/low turbulence applications at normal temperatures.

The present inventive process may be utilized in the manufacture ofsensors and instrumentation for a crude oil service operation. Themethod is simple: clean, dry, apply, insert, and monitor process, asillustrated in FIG. 1.

As an example, the manufacture of a vertical crude oil storage tanklevel sensor includes a continuous 316L, square, stainless steel outertubing that cooperates with the float carrier and all electronic sensorcomponents and switches that are activated by the movement of floatcarrier to measure the level of the liquid in the storage tank. FIG. 3shows the square tubing 50 of a digital level sensor (DLS), a floatcarrier 52 with floats members 54 attached to the carrier 52. Duringoperation, the outer surface 56 of tubing comes into contact with theinner surface 58 of the carrier 52. This sliding contact between thetubing 50 and the inner surface 58 of the float carrier 52 is adverselyaffected if paraffin or asphaltene deposits build up on these surfaces.When deposits build up on the surfaces of the components, the floatcarrier 52 does not freely move up and down the tubing 50, therebycausing false level readings in the digital level sensor. The outertubing extends the entire length of the sensor from top tank connectionto the bottom of the sensor. After assembly and testing, the sensor isdisassembled and the nano-treatment is completed in the following steps:

a. The sensor assembly including the stainless steel tubes 50, floatcarrier 52, and floats 54 are placed on horizontal support racks. Theentire sensor assembly is thoroughly cleaned on all sides with analcohol or phosphate-based detergent laden sponge or wipe 60 to removeany mill oil, dirt, grease, etc. and liberally flushed with clean water.This process step is repeated until all visual indications of surfacecontaminants are removed.

b. The assembly is thoroughly dried using clean, lint-free cloth orabsorbent paper towels.

c. Immediately after drying, the nano-treatment chemical composition ofthe present invention (SAMP) is directly applied to the clean outer tubesurfaces 56 and the inner carrier surfaces 58 of the assembly parts witha soft cloth or wipe 62 impregnated with the SAMP composition and gentlyrubbed into the outer surface 56 and inner surface 58 in order to assurecomplete chemical coverage. After approximately 1 minute of contacttime, excess SAMP composition residue is removed and the completeassembly is thoroughly dried and reassembled.

According to the present inventive method, capacitance sensors 70A, 70B,70C and 70D as shown in FIGS. 4A-4F may be treated as described above.The nano-treatment chemical composition (SAMP) is directly applied tothe clean outer surfaces 72A, 72B, 72C, 72D; the inner surfaces 74A-74D;and core elements 78A-78D as described above. It may be furtherunderstood that openings 76A, 76B, and 76C in FIGS. 4A-4C allow crudeoil to flow through the sensors, 70A-70C and become exposed to thesensor core 78A-78C. In FIGS. 4D-4F, capacitance sensor 70D has adifferent, unique design wherein rather from utilizing a generally,cylindrical tube 80A-80C, as shown in FIGS. 4A-4C, two spaced-apartstainless steel plates 90 are held in a generally parallel relationshipby two, perforated plastic sidewalls 92. A shrink wrapped printedcircuit board sensor 94, with an explosion-proof head 91 attached to oneend of the sensor, is disposed within the generally rectangularenclosure or housing formed by the two steel plates 90 and theperforated plastic side walls 92.

The nano-treatment chemical composition (SAMP) is applied to the innersurfaces 96 and outer surfaces 98 of the spaced-apart stainless steelplates 90. Crude oil flows through the perforation 93 in the sidewall 92to be read by the sensor printed circuit board 94.

Excess SAMP composition residue is removed from the treated surfaces.With the sensors 70A, 70B, 70C and 70D, it is the utilization of theanti-paraffin composition along the surfaces exposed to the crude oilwhich reduces the paraffin build-up which may affect the sensitivity ofthe sensor.

In future applications involving larger scale factory coating processes,the manual system described above will utilize more automated processes,including spray-type applicators and/or a tank dip system.

In another embodiment, a kit may be employed wherein individual wipes 60and 62 (FIG. 2) are separately sealed and robustly packaged to withstandlong-term storage and handling. Wipe 60 is a cleaning wipe having analcohol or phosphate-based detergent. Wipe 62 is impregnated with a SAMPcomposition appropriate for the application. The chemical components arenon-toxic, REACH compliant (having approximately the same environmentalcharacteristics as common isopropyl alcohol), and have no known adverseenvironmental impacts. No specialized training or Personal ProtectiveEquipment (PPE) is required for use.

A proper application of the nano-coating composition produces apermanent molecular bond that is highly stable under normal ambientconditions. However, components subjected to turbulent flow profiles inwhich basic sediment index is high (abrasive service), or those subjectto high acidity/temperature may require a re-application of theprotective coating due to surface abrasion of the metal component.

It should be understood that the AP coating is monitored to evaluate theeffectiveness of the SAMP composition coating. Recoating of componentsmay be accomplished by cleaning, drying, and applying, as describedabove.

It should be understood that the SAMP composition of the presentinvention may be enhanced by the addition of tracer additives whichimpart a “tint” or color to treated components. Such “tinting” willresult in an observable indication of the sufficiency of the componentcoating. As the “tint” intensity decreases, the operator will be able todetermine if additional coating coverage is required. Further,enhancements may include additives to produce a wider range of componentsurface characterizations including, but to limited to, corrosioninhibitors, anti-static properties, and the like. As described above,utilization of a glycol-based carrier component to the SAMP compositionmay enhance crude oil process/service applications.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to those skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed.

Those skilled in the art will recognize other embodiments of theinvention which may be drawn from the illustrations and the teachingsherein. To the extent that such alternative embodiments are so drawn, itis intended that they shall fall within the ambit of protection of theclaims appended hereto.

Having disclosed the invention in the foregoing specification andaccompanying drawings in such a clear and concise manner, those skilledin the art will readily understand and easily practice the invention.

What is claimed is:
 1. A method for treating cooperating surfaces of anelongated stainless steel tube and a float carrier of a digital levelsensor utilized in a crude oil service operation comprising the steps ofcleaning the outer surface of said tube and an inner cooperating surfaceof said float carrier to remove surface contamination; drying saidcleaned surfaces of said tube and said float carrier; applying a coat ofa Self-Assembled Monolayer of Phosphonate (SAMP) composition to saidcleaned and dried surfaces of said tube and float carrier to formtreated components; and installing said treated components into asection of a crude oil service operation, said coating reducingparaffin/asphaltene deposition on said treated components.